---
title: "CVE-2024-6387"
canonical: "https://kb.cynergy.app/space/MD/1128529923/CVE-2024-6387"
format: markdown
---
### regreSSHion and Cynergy's Remediation Capabilities

#### Introduction

OpenSSH, a widely used implementation of the Secure Shell (SSH) protocol, has recently identified a critical vulnerability designated as CVE-2024-6387, also known as regreSSHion. This vulnerability impacts the SSHD (SSH Daemon) and poses a significant threat due to its potential for remote code execution without requiring authentication. This whitepaper outlines the details of CVE-2024-6387, the potential risks it introduces, and how Cynergy can help organizations detect and remediate this vulnerability quickly and effectively.

![image-20240702-135827.png](media://04b1157a-41e8-4913-a350-06de25d73931)

#### Understanding CVE-2024-6387

##### Nature of the Vulnerability

CVE-2024-6387 is a signal handler race condition found in OpenSSH's server component (SSHD). This 

  issue arises when a client does not authenticate within the specified `LoginGraceTime`, triggering the `SIGALRM` handler asynchronously. This condition creates a race window where the SSHD's privilege separation monitor can be exploited, allowing an attacker to execute arbitrary code with root privileges without needing to authenticate.

The affected versions of OpenSSH include all versions from 8.5p1 to 9.7p1. The Common Vulnerability Scoring System (CVSS) has assigned this vulnerability a severity score of 8.1, indicating high risk due to the potential for unauthorized remote code execution.

##### Exploitation and Impact

The exploitation of CVE-2024-6387 can result in remote code execution with root privileges on the target system. This is particularly critical in environments where SSHD is configured with default settings, making numerous systems susceptible to this vulnerability. The exploit has been demonstrated on systems using Address Space Layout Randomization (ASLR) with 32-bit glibc/Linux, but it is likely exploitable in other environments, including 64-bit systems.

#### Cynergy's Role in Vulnerability Management

##### Discovery and Detection

Cynergy is equipped with advanced detection capabilities to identify the presence of vulnerabilities like CVE-2024-6387 within your infrastructure. Through continuous monitoring and automated scanning, Cynergy can detect vulnerable versions of OpenSSH and alert administrators to the potential risk. Our platform leverages comprehensive threat intelligence and real-time data to ensure timely identification of vulnerabilities.

##### Rapid Remediation

Upon detecting CVE-2024-6387, Cynergy provides actionable insights and step-by-step remediation guidance. Our platform recommends the immediate upgrade to the latest secure version of OpenSSH. For organizations unable to apply updates promptly, Cynergy suggests temporary mitigation measures, such as restricting SSH access to known and trusted IP addresses, thereby reducing the attack surface.

##### Advisory and Recommendations

Cynergy's advisory for CVE-2024-6387 includes the following steps:

1. **Upgrade OpenSSH**: It is highly recommended to install the latest version of OpenSSH to eliminate the vulnerability.
2. **Temporary Mitigation**: If an upgrade is not immediately feasible, limit SSH access to trusted IP addresses only.

### Advisory (Revised)

**OpenSSH Server Vulnerability May Allow Code Execution Without Authentication**

**Summary**

1. The OpenSSH project has disclosed a high-severity vulnerability that could enable remote code execution without authentication.
2. It is highly recommended to review and install the latest version as soon as possible.

**Details**

1. The affected versions are OpenSSH Portable 8.5p1 to 9.7p1.
2. The vulnerability is identified as CVE-2024-6387, with a CVSS score of 8.1.
3. The root cause is a signal handler race condition.
4. Exploiting this vulnerability could allow remote code execution with root privileges without authentication.
5. The exploit has been proven on 32-bit ASLR with glibc/Linux systems but is likely exploitable on 64-bit systems as well.

**Mitigation Steps**

1. It is highly recommended to review and install the latest version of the software as soon as possible.
2. As a temporary workaround, if updating is not currently possible, restrict OpenSSH service access to known addresses only.

By leveraging Cynergy's robust capabilities, organizations can ensure they stay ahead of emerging threats like CVE-2024-6387, minimizing risk and maintaining a secure operational environment.

#### Conclusion

The regreSSHion vulnerability (CVE-2024-6387) represents a significant security threat due to its potential for unauthenticated remote code execution. Cynergy provides a comprehensive solution for detecting and mitigating this vulnerability, ensuring that organizations can respond quickly and effectively to such critical security issues.

For more detailed information and the latest updates, visit the official MITRE CVE database and the [OpenSSH project page](https://www.openssh.com).